'93 F-350 4x4 w/ 35" tires?

[Paul B.]

We're building a '93 F-350, 4-door, 4WD camper. (It's going pretty slow, no dough.) I had heard on this forum that tires up to 37" should be ok on this model, maybe need to modify the front bumper. We put 35" Cooper Discoverer's on the stock 16" steel rims. We moved the front bumper forward, as the tires were rubbing pretty badly.

But now the issue is they are rubbing on the rear of the front leaf spring when turning full. What do you think?

 

[justcuz]

How much do they rub?
Would a wheel like factory Ford alcoas with a little less negative off set work?
Maybe try some wheels with zero off set and see if they work.
Lots of guys run wheel spacers to widen the track and avoid rubbing, but spacers for an F350's weight may be pricey.
I am not a spacer fan myself for two reasons, quality and extra parts. I would rather use a more positive off set wheel than spacers. There are factory dually spacers that may work for you. Factory quality I would trust.
F350 hubs and bearings are pretty stout and I am sure could handle a more positive off set wheel than factory.

 

[Regcabguy]

You need less backspacing to center the tire further out.

 

[Paul B.]

I gotta be honest with you guys I'm not that good on mechanicals. Please define "less backspacing". I'm using the stock steel wheel. How do I get less back spacing?

 

[pappawheely]

How to Measure Wheel BackSpace

The easiest way to measure backspace is to lay the wheel face down onto the ground so the backside of the wheel is facing up. Take a straight edge and lay it diagonally across the inboard flange of the wheel. Take a tape measure and measure the distance from where the straight edge contacts the inboard flange to the hub mounting pad of the wheel. This measurement is backspace. The photo below shows three wheels with 2",3", & 4" backspace.

Items required to measure wheel backspace:

Wheel BackSpace
Tape measure

Straight edge

Wheel w/o tire (preferred)

- See more at: http://www.4wheelparts.com/tire-whe...-offset-backspacing.aspx#sthash.lq2ICa9d.dpuf

 

[Happykamper]

This type thread is why I love this forum. And the people on it. Just good solid hey let me explain it to you. I have gotten so much great info about things I had no clue on.
You folks are great

 

[justcuz]

I suppose I should have clarified my comments. My bad for assuming you would know what I meant.

Backspacing or offset is how much of the wheel is either inside or outside the wheel mounting surface (WMS)
Negative offset is toward the inside, positive offset is toward the outside and zero offset is even on both sides.

It is measured as papawheely explained and can be done on both sides of the wheel.

Most factory wheels are offset to the inside or negative. I thought the factory Alcoa aluminum wheels were zero and many aftermarket wheels can be ordered with whatever you want.

Positive offset will move the wheel and tire assembly away from the spring and centerline of the WMS.

 

[Paul B.]

Now I see. Seems my mistake was throwing a larger tire on the stock rim without consideration of the wheel backspacing. Hoping not to replace the rims. (I like the steel rims.) I recall seeing wheel balancers on Pappawheely's rig. Will these add any significant offset? Besides price, what are the downsides to spacers?

Edit: Whoa Nellie! Spacers for an 8 lug wheel are super pricey. New wheels might be cheaper. There does seem to be at least an inch of additional length on the stock threaded studs.... maybe.....? I got a killer deal on the 35" Cooper tires, but they are 16" If I was to purchase new rims, I would likely want 16.5" or 17" as those sizes seemed to offer more tire choices. This might turn out to be a costly error.

Much thanks in advance. You guys are a great help to a neophyte like myself.

 

[tgreening]

Been a while since I've crawled around under a 90s era Ford, but you might want to give your front knuckles a look-see and see if they have steering stops on them. Google > Images > looky looky.

If you are only rubbing just a bit adjusting these might get you out of trouble, at least until you decide on a permanent solution. It will cost you turning radius, but not a dime out of your wallet.

Unless you want to run surplus militaries in the 37" dept I'd stay away from 16.5 rims. They really don't offer much for selection in the taller category. If you don't mind the militaries they're fairly easy to get, and cheap compared to what's available on the civilian market. Heavy as hell, stiff as a board, not super great in any traction category, but cheap, easy to get and wear fairly well.

 

[pappawheely]

Been a while since I've crawled around under a 90s era Ford, but you might want to give your front knuckles a look-see and see if they have steering stops on them. Google > Images > looky looky.

If you are only rubbing just a bit adjusting these might get you out of trouble, at least until you decide on a permanent solution. It will cost you turning radius, but not a dime out of your wallet.

Unless you want to run surplus militaries in the 37" dept I'd stay away from 16.5 rims. They really don't offer much for selection in the taller category. If you don't mind the militaries they're fairly easy to get, and cheap compared to what's available on the civilian market. Heavy as hell, stiff as a board, not super great in any traction category, but cheap, easy to get and wear fairly well.

All good advice. I would like to add that 16.5's have a different design that does not grip the tire bead well when aired down.

 

[justcuz]

All factory rims are not the same. Luckily all domestic 8 lug wheels in your vintage were the same bolt pattern.
You may want to go to a wrecking yard and see if other sets of 8 lug wheels have less back spacing than the ones you have. These are the Ford factory Alcoa aluminum wheels. I think they are 7" wide and have less negative backspacing than steel wheels. The center holes in the wheels are not all the same so be mindful of that. These wheels are on a Chevy. I agree with the 16.5 tire comment, unless you are running bead locks, 16.5 tires and wheels are not worth it off road. 16.5 wheels have no safety bead, so the tire can come unseated from the wheel very easily at low tire pressure. Keep your 35" tires and shop around for wheels. Wheels in junkyards are cheap and easy to measure backspacing because most are already off the vehicle.

 

[Paul B.]

I out now to find a set of 16" wheels with better backspacing. I like the price and look of plain old steel wheels, but we'll see.

Thanks guys. This forum is a great resource because of the great people on here.

 

[justcuz]

Ford vans used the 8x6.5 bolt pattern long after the Super Duty went metric (99?).

Van wheels may have less backspacing, not sure but maybe.

 

[gmacmt]

If you want to get 37's cheap and "easy" you can buy a set of HMMWV surplus wheels and tires for about 200/corner brand new. Like, never touched ground new. They are a lot cheaper with 90% tread, like ~150/corner. Then you can buy wheel adapters to satisfy any backspace requirements you have from that wheel. All the info is out there, check out my build thread if you are interested. I have 1000 into 5 wheels and tires, plus 500 for the adapters.

Downside is that there are about 4 models of tires (Pitbull, Super Swamper, BFG Baja TA, Goodyear MTR?) out there for 16.5" wheels, and they might not be around forever. And only one of them is good and cheap. As long as you are OK with the BFG baja TA though, it should be a cheap reliable source for years to come.

Suppliers are Feltz Tire in Wisconsin for the wheels and tires (might be someone closer in the LA area to save on shipping) and motorsport tech for the adapters.

 

[justcuz]

100dollarman out west here for tires probably wheels too. I got 16.5 wheels and tires I can't give away here.

He wants to keep his 16" wheel 35" tires and likes steel wheels.